The J. Linsley Gressitt Center for Research in Entomology is the premier collection of Pacific insects in the world. No other collection has the holdings, the scope, or the representation of specimens from the Pacific and surr­ounding areas. Greatest holdings are from the Hawaiian Islands, SE Asia, New Guinea, and the Philippines. The collection houses an estimated 14 million specimens and holds over 17,500 types mostly from the Pacific, but also those resulting from early Hawaiian-based biological control explorations from around the world.

The Entomology Collection documents many of the great explorations of the past, from the early explorers through expeditions such as Galathea, Mangarevan, and Pacific Entomological Survey (Polynesia), as well as critically important biological survey s such as Fauna Hawaiiensis, Insects of Micronesia, Southwest Pacific and Southeast Asia arthropods of medical importance, the Terrestrial Arthropod Survey of Fiji, and numerous recent arthropod surveys of French Polynesia. Also documented are smaller but equally important early individual projects and explorations such as Insects of Samoa, New Guinea, Insects of Guam, subantarctic islands. Large theoretical projects also are vouchered in these collections, for example, ship trapping and air trapping projects that showed that insects can disperse through the Pacific using air currents. The collections themselves have been most currently used to further the understanding of island biogeography. None of these are duplicated elsewhere.

The collection holds large but unknown numbers of endangered, threatened and extinct species. For virtually all arthropods, not enough research has been completed to even begin listing endangered or threatened species. So this is a critical resource for understanding the previous working of and future problems associated with the disruption of natural processes. One example is the Hawaiian beetle collections of which possibly 75% can be considered for listing as endangered or threatened. Strongly documents pre-contact Hawaiian natural history (for example, beetles taken in excavations of early Hawaiian fireplaces, etc.). Important holdings in medical entomology, especially studies in disease vectors (e.g., parasites) in the South Pacific and Southeast Asia as a result of World War II. Much of the active collecting phase in the western Pacific & Asia was conducted in relatively intact environments that since have been strongly modified increasing the val­ue of the representative specimens.